Measurement of two-phase flow using particle image velocimetry

• Main Author: Cosgrove, John Augustine
• Published: University of Edinburgh 1997
• Subjects: 551.9
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.645014

A theoretical and experimental study has been carried out into the measurement of two-phase flows, with particular emphases placed on the analysis and assessment of factors which affect the data obtained from the experiments. Statistical theory has been developed to account for the recorded intensity of side-scattered light from a particle due to: (a) the integration effects of the pixels in the CCD sensor, (b) the quantization effects of the electronics associated with CCD cameras and (c) the position of the particle in a scanning-beam PIV illumination system. The theory was found to agree well with experiment and indicates that for typical PIV experimental parameters, the variation of light recorded due to a particle's random position in the laser sheet is an order of magnitude higher than the variation of light intensity due to the integration effects of the CCD sensor. A further experiment indicated that the variation of intensity due to the light scattering characteristics of quartz sediment particles is of the same order of magnitude as the variation due to the position of the particle in the laser sheet. An automatic system was developed to locate and analyse the particle images of both phases. The primary difficulty for the system was found to be in separating the phases. Experiments were performed to determine statistical confidence levels for this purpose. The analysis method was developed and applied to experiments involving the measurement of two-phase (sediment/water) flow over a rippled-sand bed. For this purpose, a flexible, convenient and robust PIV illumination system was built. The results obtained are discussed to indicate the validity of the method and show that it works well when applied to a practical two-phase flow experiment.